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Wear Properties of Cryogenic Treated Electrodes on Machining Of En-31

Wire Cut Electrical Discharge Machining (WEDM) is a non-conventional thermal machining process which is capable of accurately machine alloys having high hardness or part having complex shapes that are very difficult to be machined by the conventional machining processes. The WEDM finds applications in automobiles, aero–space, medical instruments, tool and die industries, etc. The input parameters considered for WEDM are pulse on time, pulse off time, flushing pressure, servo voltage, wire feed rate and wire tension. Performance of WEDM is mainly assessed by output variables such as, material removal rate (MRR), kerf width (Kw) and surface roughness (Ra) of the work piece being machined. Looking at the need of a suitable optimization model, the present work explores the feasibility of machine learning concepts to predict optimum surface roughness and kerf width simultaneously by making use of experimental data available in the literature for machining of Hastelloy C– 276 using WEDM. In most of the literatures, single objective optimization has been carried out for predicting optimum cutting parameters for WEDM. Hence, the present work presents a methodology that makes use of a machine learning algorithm namely, gradient descent method as an optimization technique to optimize both surface roughness and kerf width simultaneously (multi objective optimization) and compare the results with the existing literatures. It was observed that the input parameters such as pulse on time, pulse off time, and peak current have significant effect on both surface roughness and kerf width. The gradient descent method was successfully used for predicting the optimum values of response variables.

Experimental Study to Assess the Effect of Electrode Bottom Profiles while Machining Inconel 718 through EDM Process

The emergence of white layer in each process of Electric Discharge Machining (EDM) becomes the focus of attention of the experts. It is harder than the base metal would be advantageous to withstand friction engine components, such as the plastic molding industry. From various studies it has been reported that the increase in the value of hardness of white layer either due to migration of the electrode material and dielectric fluid to the white layer. This paper discusses the influence of electrodes Cu, CuCr and graphite as well as jatrophacurcas dielectric fluid to the surface of the material SKD 61, microhardness of the white layer, Tool Wear Rate (TWR) of Material Removal Rate (MRR), Surface roughness (Ra) and the microstructure. Initial studies conducted are the transesterification and characterization of jatrophacurcas to determine the dielectric strength and the content of metal elements. Furthermore, the EDM testing is done to dies steel of SKD 61 using the electrodes of Cu, CuCr and Graphite. The use of jatrophacurcas yield the best MRR when using Graphite electrodes followed Cu last CuCr. While the smallest TWR produced by Cu electrode, CuCr and then the highest is Graphite. The relative wear which is the ratio TWR with MRR, for the three types of electrodes is always great at a small current then decreases and then tends to be stable with the increase of electric current. Jatrophacurcas for the three types of electrodes provide higher TWR than kerosene. This means that migration of materials is beneficial because larger material, but in terms of the geometric accuracy of the product can lead to decreasing of dimensional tolerances. Vickers hardness values of white layer is achieved by CuCr electrodes, Graphite lowest. Microstructural observation results of EDM white layer using graphite electrodes produce a more uniform thickness than the white layer using Cu and CuCr electrodes. The conclusion of this study that jatrophacurcas can be used as a dielectric fluid in EDM process, because electrode wear during EDM process is relatively high compared with kerosene that is mean more profitable in the surface treatment process of dies steel of SKD 61.

In the digital manufacturing era, to forbid the challenges and complexity in manufacturing of the geometrically complicated shapes or machining the harder materials or precise cutting of materials, electrical discharge machining has been used by the manufacturing sectors. The output performance of the electric discharge machining depends on its input process parameter values. So in this current research, these input parameters such as supply current, pulse on time and pulse off time have been considered and optimized its value for achieving higher material removal rate, enhanced surface roughness and lesser tool wear rate for Al6061 SiC stir casted metal matrix composites using selective breeding algorithm. Selective breeding algorithm is applied to optimize the said multiple performance characteristics. This experimental research revealed that current value is having major influence over the output performance parameter.KeywordsAl6061Metal matrix compositeElectrical discharge machiningSelective breeding algorithm

Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. In this research work, investigations were carried out on the machining of AISI D2 tool steel under conventional EDM and cryogenically cooled EDM process (CCEDM). The input process parameter such as current (Ip), pulse on time (Ton) and gap voltage (V) were investigated and the output responses like electrode wear ratio, metal removal rate and surface roughness were explored. Experiments were conducted using L18 orthogonal array in EDM machine. Experimental results showed reductions in the electrode wear of 16% over CCEDM process. A grey relational analysis was used to solve the EDM process with multi performance characteristics to optimize EDM parameters.

At present, the growing needs and design requirements with significant weight savings as well as high strength-to-weight ratio as compared to conventional materials raised a growing interest towards composite materials. Metal matrix composites (MMCs) are extensively used in fields like aerospace, automobiles and army-defence applications due to their high specific strength, low coefficient of thermal expansion, wear resistance, high durability, excellent physical and mechanical properties. The filler reinforcements like SiC, TiC, Al2O3 improve the stiffness, specific strength, creep properties of MMCs, but the presence of such hard reinforcements makes MMCs difficult to machine through conventional machining processes. Wirecut electrical discharge machining (WEDM) is highly precise thermoelectrical process and is considered ideal for machining very hard materials, intricate geometries and tooling. This paper reviews the researches in WEDM of metal matrix composites and the relation between different process parameters like pulse on time, pulse off time, wire feed rate,voltage, wire tension, dielectric flow rate on the machining performances such as material removal rate (MRR), Kerf widthand surface roughness (SR). The future trends in WEDM researches were also recommended in this paper.

Wire Electrical Discharge Machining (WEDM) is a versatile process to generate intricate and complex shapes on conductive work material with high dimensional accuracy and surface finish. Since the process is stochastic, its input parameters play critical role for achieving desired accuracy and precision of the component. Inconel 718, High-Strength-Temperature-Resistant (HSTR) material, has wide applications in the field of aerospace, automobile, mould making and medical industries. Hence, machining of Inconel 718 using WEDM is a challenging task. Also experimentation on Inconel 718 with WEDM is costly as well as time consuming process. Therefore to study the behavior of WEDM process with different process parameters for effective and efficient operation, process modeling and simulation using appropriate software is highly essential. In the present investigation, a 3-D single spark finite element thermal model for WEDM process has been developed using ANSYS software. This model has some more realistic assumptions like heat flux following Gaussian distribution and spark radius as a function of time and energy. Plasma incident region is meshed by keeping elemental size equal to one tenth of entire plasma radius, so that exact ten elements can be fitted. Identified elements were thermally loaded by applying element wise different temperatures for getting more accurate temperature distribution profile. This profile was found to be having crater shape matching with earlier Finite Element Models (FEM) available in the literature. Along with the shape, it also helps to decide the elements having temperatures greater or equal to melting point leading to estimate Material Removal Rate (MRR). Later on single spark MRR can be used to estimate multi-discharge-MRR by calculating pulse rate. Model MRR is validated with the experimental MRR which show a very good agreement, but little variation. This variation in the modeling could possibly due to assumptions like no delay in ignition, non-deposition of recast layer (100% flushing efficiency), etc. The factors like incomplete flushing of debris and inter-electrode gap arcing cause the variation in machining conditions thus reducing the actual MRR. In the present investigation, the use of dielectric is considered only for convection, but in reality, it acts as an insulator, coolant and also as debris remover. Melting and vaporization of material is the main phenomena for material removal. Dielectric fluid partially removes the molten metal because at the same time, the molten metal is under very high pressure due to plasma channel. Its adhesive property resists the material removal. It is very difficult to incorporate all real effects in the model, however the obtained results in the present study show good agreement between model MRR and experimental MRR within 10% variation.

EDM machinability and surface roughness analysis of TiB2 using copper electrodes

Electric discharge machining of Al–SiC metal matrix composites using rotary tube electrode

Electrical Discharge Machining (EDM) is a non-conventional machining process widely used to manufacture hard material components which are not easily machined by conventional machining processes. Several modeling approaches have since long been proposed to characterize the EDM process, based on the electro-thermal phenomena that occur. Several of these early models are analytical models that have the major advantage of providing predictions of process performance based on analytical solutions. Unfortunately, their derivation often demands a number of assumptions and simplifications, which can limit the scope and precision of the predictions obtained. Two of the most known analytical models are based on different heat sources: a point heat source [1], and a uniform disk heat source [2]. In this paper, these two analytical EDM models are analyzed and compared with more elaborated numerical models in which specific modeling assumptions are lifted; the objective is to quantify the influence of each of these assumptions on the final result. Numerical simulations are based on the finite element method, which enables to study the influence of different temporal pulse shapes, the spatial intensity distribution, the temperature dependency of the thermal coefficients, and in particular the influence of the way latent heat is taken into account. The results are analyzed in terms of the predicted material removal rate (MRR), depth and radius of the crater. A comparison is presented between the two theoretical results [1], [2], and those obtained by the more elaborated numerical models. At the same time, a comparison is also made with some experimental data from literature.

Investigation of process parameters optimization in die-sinking and wire cut EDM to improve process performance using taguchi technique

This paper presents the experimental investigation of the machining characteristics of AISI D2 tool steel on the electrical discharge machining (EDM) process by replacing the copper electrode tool with carbon nanotube (CNT) fused electrode, and checking for improvement in machinability factors like material removal rate (MRR), electrode wear rate (EWR) and surface finish (SR). The problems of high electrode wear in EDM machining, such as poor dimensional and shape accuracy of the machined part, need to be addressed. The work material is spark machined with pure copper and CNT-infused copper electrodes by varying parameters on an EDM. The results of the machining characteristics with and without the CNT are compared and analysed using Taguchi analysis. This study investigates the optimisation of EDM parameters for AISI D2 tool steel using TOPSIS method. Analysis of variance (ANOVA) and F-test are used to check the validity of regression model and determine the significant parameter affecting the surface roughness.

Effect of High Chromium Platinum steel with composite Copper-Tin material electrode on Electric Discharge Machining Performance

Electrical discharge machining (EDM) is a nonconventional machining process widely applied for the manufacture of intricate shapes in hard materials which are not easily machined by conventional machining processes. The production of geometrically complex EDM electrodes is difficult, time consuming, and it can account for about 50 % of the total process costs. Selective laser sintering (SLS) can be an alternative technique to produce EDM electrodes in a faster way. This work conducted an experimental study on the performance of EDM electrodes made by SLS using pure copper, bronze–nickel alloy, copper/bronze–nickel alloy, and steel alloy powders. Important EDM performance measures such as material removal rate and volumetric relative wear were investigated and discussed for finishing, semifinish, and roughing regimes. This work contributes with an insight into the production of EDM electrodes via selective laser sintering, as an alternative technique to conventional machining processes, as well as to evaluate the performance of the electrodes, and also provide directions for future research on this field.